The present invention relates generally to the field of welding systems, and particularly to pulsed gas metal arc welding systems (GMAW-P), also known as pulsed metal inert gas (pulsed MIG) welding systems.
Arc welding systems generally comprise a power supply that applies electrical current to an electrode so as to pass an arc between the electrode and a work piece, thereby heating the electrode and work piece to create a weld. In many systems, such as gas metal arc welding systems (GMAW), the electrode consists of a wire which is advanced through a welding torch. As the electrode is heated by the arc, the electrode melts and is joined to molten metal of the work piece to form the weld. By controlling the supply of voltage and current to the electrode, a GMAW system may control the manner in which the electrode is melted and deposited by the arc. For example, the voltage supply to the electrode may be held constant, while the current supply is varied so as to maintain a constant arc length independent of the distance between the contact tip and the work piece. A GMAW system may also supply voltage and current to an electrode in a periodic or pulsed manner, known as pulsed gas metal arc welding (GMAW-P) or pulsed metal inert gas (pulsed MIG) welding.
In a GMAW system, the arc melts the end of the electrode into a molten ball and transfers the molten ball onto the work piece. Rather than provide a single constant voltage-controlled or constant current-controlled arc, GMAW-P welding systems supply voltage and current to the electrode according to a periodic pattern as a power pulse. For example, a GMAW-P welding system may supply a constant low voltage in a first phase (the background phase), and then supply a constant high voltage in a second phase (the peak phase). In such a way, an arc may provide only enough power to melt the electrode in the background phase, while providing sufficient power to transfer the molten electrode material to the work piece in the peak phase. A GMAW-P system may allow a variety of parameters to be programmed to affect the power applied to form the weld, such as constant voltage levels, fixed current beginning points, constant current ramp rates, minimum and maximum current limits, time allowed for each phase, and so forth. Thus, pulses and the applied power may not be identical, varying the consistency of the GMAW-P welding arc and weld quality. The GMAW-P welding arc may be affected by the components of the GMAW-P system, the power source, environmental conditions at the work piece or welding torch, and operator skill. These factors, among others, may affect the quality of a weld.